The present invention relates to a circuit arrangement for the digital control of operating functions via sensor electrodes, especially in radio and television receivers.
Operational arrangements of the aforementioned kind serve to avoid mechanical setting procedures, to improve operational convenience by the use of sensor electrodes, and to reduce the investment otherwise involved for the connection of remote-control circuits.
It is already known to employ, for this purpose, electronic information storages and bistable flip-flop stages. Information storages are known to comprise one or more control inputs via which a sequential, in particular stepwise control of the output circuit state which is capable of being stored, can be effected either in the forward, the backward, or in both directions. The output circuit serves as the control element of the function to be performed. It may, in many cases, be considered as a digital-to-analog converter.
It is also known, via the control input of an information storage, electronic stepping switch, or ring counter capable of being forwardly controlled in n steps, to effect the resetting by respectively one step of a burst consisting of n-1 stepping pulses. This method can be used equally well for the electronic frequency setting or channel selection purpose. Further, when using known channel selection techniques, it should be noted that in electronic stepping arrangements it is customary to employ the control in the sequential manner as described hereinbefore, but also in parallel therewith, via sensor electrodes, with a direct setting of the desired storage position. The combination of these two kinds of operation, namely the direct and sequential setting of the control element is known in the art, as is the indication of the storage condition of the electronic stepping circuit, coupled thereto, by means of several signal lamps, light-emitting diodes, counter tubes, or other indicating arrangements. Moreover, it is known as electronic stepping circuits there may also be used ring counter circuits, as well as binary counting circuits employing flip-flop chains. It has proved suitable, for the channel selection in radio and television receivers, to use electronic stepping circuits having individual outputs similar to those of a ring counter, and to use for the more sensitive control of otherwise continuous operating functions, the binary encoded flip-flop chains. For the electronic stepping circuits of the first-mentioned kind, integrated switching circuits are already available which are designed, for example, to effect the switchover to four television channels with the aid of four bistable electronic switches with the inputs thereof capable of being applied to sensor electrodes, and with the outputs thereof capable of being applied to tuning potentiometers. Upon simultaneously touching a sensor electrode and the common counter electrode, the connected potentiometer is applied to the necessary voltage, and also the waverange switch of the television tuner is simultaneously connected via a second output, to the operating voltage together with the associated indicating element. Especially for remote-control purposes it is possible that in this integrated circuit the output of one stage can be connected to the successively following input of the next stage via a capacitor to form a ring counter circuit. Via one common input of all bistable electronic switches, the circuit may then be controlled in a stepwise manner with the aid of sequential pulses originating e.g. with a remote-control circuit. In the already previously mentioned binary encoded step counters, the flip-flops, however, are not brought into the desired binary combination by way of direct setting, but likewise by way of sequential control, in which case an interrogating circuit interrupts the control process upon reaching the target combination. This interrogating method as well as the not yet employed direct setting method, however, involve a considerable investment.